Circuit board and manufacturing method thereof

ABSTRACT

The disclosure provides a method for manufacturing a circuit board, which includes: (1) providing a substrate, forming a through hole in the substrate; (2) filling the through hole with a conductor to form a conductive hole; (3) providing a peelable film to cover the substrate; (4) forming a groove by laser, the groove including a concave portion; (5) performing a surface treatment on a wall of the groove; (6) removing the peelable film; (7) forming a seed layer; (8) making a circuit layer to obtain a circuit board unit, the circuit layer including a connection pad, the connection pad shaped as a conductive protrusion which surrounds and is electrically connected to the conductor; (9) repeating step (1) to step (8) at least once; and (10) laminating the circuit board units. The disclosure also provides a circuit board.

FIELD

The disclosure relates to a circuit board and a manufacturing methodthereof.

BACKGROUND

As the frequency of signal transmission and the number of input/outputinterfaces increase, higher requirements are placed on the signaltransmission loss of the circuit board and the reliability of thecircuit layer. In the traditional circuit layer manufacturing method,the subtractive method and the improved semi-additive method have poorability to produce fine circuit layers, and the cost of thesemi-additive method is high.

SUMMARY OF THE DISCLOSURE

In view of the above, it is necessary to provide a circuit board and amanufacturing method thereof to solve the above problems.

A circuit board manufacturing method includes the following steps:

(1) Provide a substrate, and make a hole in the substrate to form athrough hole;

(2) Fill the through hole with a conductor to form a conductive hole;

(3) Provide a peelable film to cover one side of the substrate;

(4) Form a groove in the peelable film and the substrate by laserablation, the groove includes a concave portion, the concave portion islocated at the conductive hole, and the diameter of the concave portionis larger than the diameter of the conductive hole to expose a portionof the conductor;

(5) Perform a surface treatment on a side wall and bottom wall of thegroove to improve roughness;

(6) Remove the peelable film;

(7) Form a seed layer on the side wall and bottom wall of the groove;

(8) Make a circuit layer in the groove to obtain a circuit board unit,the circuit layer includes a connection pad located in the concaveportion, the connection pad is shaped as a conductive protrusion whichsurrounds and is electrically connected to the conductor;

(9) Repeat step (1) to step (8) at least once; and

(10) Laminate the at least two of the circuit board units.

Further, in step (5), the side wall and bottom wall of the groove areprocessed by a plasma surface treatment machine.

Further, in step (7), the seed layer is formed by chemical vapordeposition or physical vapor deposition.

Further, after step (8) and before step (9), the method further includesthe steps of: forming a metallization layer on the surface of thecircuit layer.

Further, in step (1), one side of the substrate is connected to acarrier board through a separable film.

A circuit board includes at least two stacked circuit board units, andeach of the circuit board units includes a substrate and a circuitlayer. The substrate is provided with a conductive hole, and a conductoris provided in the conductive hole. A groove is provided on one side ofthe substrate. The groove includes a concave portion. The concaveportion is located at the conductive hole, and the diameter of theconcave portion is larger than the diameter of the conductive hole toexpose a portion of the conductor.

The circuit layer includes a connection pad located in the concaveportion, and the connection pad is shaped as a conductive protrusionwhich surrounds and is electrically connected to the conductor. Thecircuit layer is located in the groove, and the conductive holeelectrically connects the circuit layers of two adjacent circuit boardunits.

Further, a metallization layer is provided on the surface of the circuitlayer.

A circuit board manufacturing method includes the following steps:

Providing a substrate, and opening a hole in the substrate to form athrough hole;

Filling the through hole with a conductor to form a conductive hole;

Providing two peelable films covering opposite sides of the substrate,respectively;

Forming grooves in the two peelable films and two sides of the substrateby laser ablation, each groove including a concave portion, the concaveportion located at the conductive hole, and the diameter of the concaveportion larger than the diameter of the conductive hole to expose aportion of the conductor;

Performing a surface treatment on a side wall and a bottom wall of eachof the two grooves to improve roughness;

Removing the two peelable films;

Forming a seed layer on the side wall and the bottom wall of each of thetwo grooves;

Forming a circuit layer in each of the two grooves to obtain a circuitboard, the circuit layer including a connection pad in the concaveportion, the connection pad shaped as a conductive protrusion whichsurrounds and is electrically connected to the conductor.

A circuit board includes a substrate and two circuit layers. Thesubstrate is provided with a conductive hole. The conductive hole isprovided with a conductor.

The substrate is provided with a groove on both sides, and each of thetwo circuit layers is respectively provided in the corresponding one ofthe two grooves. The groove includes a concave portion. The concaveportion is located at the conductive hole, and the diameter of theconcave portion is larger than the diameter of the conductive hole toexpose a portion of the conductor. The circuit layer includes aconnection pad located in the concave portion. The connection pad isshaped as a conductive protrusion, and the conductive hole electricallyconnects the two circuit layers. The manufacturing method of the circuitboard of the present disclosure is relatively simple and themanufacturing cost is low. The circuit of the manufactured circuit boardis formed in the groove, and the groove is formed by laser ablation.Therefore, the line width of the circuit layer is stable and theprecision is high. The connection pad of the circuit board of thepresent disclosure is a conductive protrusion to improve the conductiveyield.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a through hole formed in a substrateaccording to a first embodiment of the present disclosure.

FIG. 2 is a cross-sectional view of the through hole of the structureshown in FIG. 1 filled with a conductor.

FIG. 3 is a cross-sectional view of the structure shown in FIG. 2covered with a peelable film.

FIG. 4 is a cross-sectional view of a groove formed in the peelable filmand a cover layer of the structure shown in FIG. 3

FIG. 5 is a cross-sectional view of the structure shown in FIG. 4 withthe peelable film removed.

FIG. 6 is a cross-sectional view of a seed layer formed in the groove ofthe structure shown in FIG. 5.

FIG. 7 is a cross-sectional view of a circuit layer formed in the grooveof the structure shown in FIG. 6.

FIG. 8 is a cross-sectional view of the structure shown in FIG. 7 with aseparable film and a carrier board removed.

FIG. 9 is a cross-sectional view of a metallization layer formed on thecircuit layer of the structure shown in FIG. 8.

FIG. 10 is a cross-sectional view of a circuit board according to thefirst embodiment and a third embodiment of the present disclosure.

FIG. 11 is a cross-sectional view of a through hole formed in asubstrate according to a second embodiment of the present disclosure.

FIG. 12 is a cross-sectional view of the structure shown in FIG. 11after a groove is formed.

FIG. 13 is a cross-sectional view of a circuit board according to thesecond embodiment and a fourth embodiment of the present disclosure.

SYMBOL DESCRIPTION OF MAIN COMPONENTS

Circuit board 200, 300

Circuit board unit 100

Substrate 10

Separable film 101

Carrier board 102

Through hole 11

Conductor 111

Conductive hole 12

Peelable film 13

Groove 15

Concave portion 151

Seed layer 16

Circuit layer 20

Connection pad 21

Metallization layer 22

The following specific embodiments will further illustrate the presentdisclosure with reference to the above drawings. The technical solutionsin the embodiments of the present disclosure will be described clearlyand completely in conjunction with the drawings in the embodiments ofthe present disclosure. Obviously, the described embodiments are only apart of the embodiments of the present disclosure, not all of them.Based on the embodiments of the present disclosure, all otherembodiments obtained by a person of ordinary skill in the art withoutcreative work fall within the protection scope of the presentdisclosure.

It should be noted that when an element is considered to be “connected”to another element, it may be directly connected to another element orthere may be an element that is centrally located at the same time. Whenan element is considered to be “provided on” another element, it may beplaced directly on another element or there may be an element placed inthe middle at the same time.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by those skilled in thetechnical field of the present disclosure. The terminology used in thedescription of the present disclosure herein is for the purpose ofdescribing specific embodiments, and is not intended to limit thepresent disclosure. The term “and/or” as used herein includes any andall combinations of one or more related listed items.

FIGS. 1 to 10 refer to a first embodiment of the present disclosure of amethod for manufacturing a circuit board, the method includes thefollowing steps.

In the first step, referring to FIG. 1, a substrate 10 is provided, anda hole is formed in the substrate 10 to form a through hole 11.

In this embodiment, one side of the substrate 10 is connected to acarrier board 102 through a separable film 101 to facilitate processing,but it is not limited to this. In other embodiments, the separable film101 and the carrier board 102 may be omitted.

The substrate 10 is a low dielectric resin material, preferably apolyester polymer base material or a polyether polymer base material,such as polyether ether ketone (PEEK), liquid crystal polymer (LCP),etc.

In this embodiment, the through hole 11 is formed by laser processing.It can be understood that, in other examples, the through hole 11 mayalso be formed by mechanical processing.

In the second step, referring to FIG. 2, the through hole 11 is filledwith a conductor 111 to form a conductive hole 12.

The conductor 111 is a conductive material such as conductive paste.

In the third step, referring to FIG. 3, a peelable film 13 is providedfor covering one side of the substrate 10.

In this embodiment, the peelable film 13 covers the side of thesubstrate 10 facing away from the carrier board 102.

The peelable film 13 is a resin material such as polyimide (PI),polyethylene terephthalate (PET), polyethylene naphthalate (PEN), etc.

In the fourth step, referring to FIG. 4, a groove 15 is formed in thepeelable film 13 and the substrate 10 by laser ablation.

The groove 15 includes a concave portion 151. The concave portion 151 islocated at the conductive hole 12, and the diameter of the concaveportion 151 is larger than the diameter of the conductive hole 12 toexpose a portion of the conductor 111.

The groove 15 is formed by laser ablation to accurately control the linewidth and stability and facilitate the impedance control tolerance. Anexcimer laser is preferably used to finely adjust the opening size ofthe groove 15.

In the fifth step, a surface treatment is performed on a side wall and abottom wall of the groove 15 to increase roughness.

In this embodiment, the side wall and the bottom wall of the groove 15are processed by a plasma surface treatment machine to remove residueformed from laser ablation and improve the roughness and an activatingeffect.

It can be understood that, in other embodiments, sandblasting may alsobe performed.

In the sixth step, referring to FIG. 5, the peelable film 13 is removed.

In the seventh step, referring to FIG. 6, a seed layer 16 is formed onthe side wall and the bottom wall of the groove 15.

In the present embodiment, the seed layer 16 is formed by chemical vapordeposition (CVD) or physical vapor deposition (PVD). The thickness ofthe seed layer 16 ranges from 0.08 microns to 2 microns. The seed layer16 may be made of nickel, copper, gold, graphite, titanium, silver, orother materials.

Since the side wall and the bottom wall of the groove 15 have highroughness, it is easy to form the seed layer 16, while it is difficultto form the seed layer 16 on other parts.

In the eighth step, referring to FIG. 7, a circuit layer 20 is formed inthe groove 15 to obtain a circuit board unit 100.

The circuit layer 20 includes a connection pad 21 formed in the concaveportion 151. The shape of the connection pad 21 is a conductiveprotrusion, which surrounds and is electrically connected to theconductor 111.

The circuit layer 20 can be formed by chemical plating, electroplating,sputtering, ion plating, or the like. It can be understood that duringplating, the circuit layer 20 is connected to the plating power sourceby adding leads.

In the ninth step, referring to FIG. 8, the separable film 101 and thecarrier board 102 are removed.

It can be understood that in other embodiments, if the separable film101 and the carrier board 102 are omitted, the ninth step is omitted.

In the tenth step, referring to FIG. 9, a metallization layer 22 isformed on the surface of the circuit layer 20. The metallization layer22 is formed by tin (immersion tin). In other embodiments, it may alsobe silver or other soft metals. The metallization layer 22 is used toensure the reliability of electrical conduction of multiple layers ofthe circuit board units 100 in subsequent steps. It can be understoodthat in other embodiments, the tenth step may be omitted.

In the eleventh step, the first through tenth steps are repeated atleast once.

In the twelfth step, referring to FIG. 10, at least two of the circuitboard units 100 are laminated to obtain the circuit board 200.

Referring to FIG. 11 to FIG. 13, a second embodiment of the presentdisclosure of a method for manufacturing a circuit board includes:

In the first step, referring to FIG. 11, a substrate 10 is provided, anda hole is formed in the substrate 10 to form a through hole 11.

In the second step, the through hole 11 is filled with a conductor 111to form a conductive hole 12.

In the third step, two peelable films 13 are provided to cover oppositesides of the substrate 10.

In the fourth step, referring to FIG. 12, a groove 15 is formed in eachof the opposite sides of the substrate 10 and each of the two peelablefilms 13 by laser ablation.

The groove 15 includes a concave portion 151. The concave portion 151 islocated at the conductive hole 12, and the diameter of the concaveportion 151 is larger than the diameter of the conductive hole 12.

In the fifth step, a surface treatment is performed on a side wall and abottom wall of each of the two grooves 15 to increase roughness.

In the sixth step, the two peelable films 13 are removed.

In the seventh step, a seed layer is formed on the side wall and bottomwall of each of the two grooves 15.

In the eighth step, referring to FIG. 13, a circuit layer 20 is formedin each of the two grooves 15 to obtain a circuit board 300.

Each of the circuit layers 20 includes a connection pad 21 located inthe concave portion 151. The shape of the connection pad 21 is aconductive protrusion, and the two circuit layers 20 are electricallyconnected through the conductor 111.

FIG. 10 is a third embodiment of the present disclosure of the circuitboard 200. The circuit board 200 includes at least two stacked circuitboard units 100. Each of the circuit board units 100 includes asubstrate 10 and a circuit layer 20.

The substrate 10 has a conductive hole 12 penetrating therethrough. Aconductor 111 is provided in the conductive hole 12.

A groove 15 is provided on one side of the substrate 10. The groove 15includes a concave portion 151. The concave portion 151 is located atthe conductive hole 12, and the diameter of the concave portion 151 islarger than the diameter of the conductive hole 12 to form a steppedhole structure, to expose a portion of the conductor 111.

The circuit layer 20 is located in the groove 15. The circuit layer 20includes a connection pad 21 located in the concave portion 151. Theshape of the connection pad 21 is a conductive protrusion. Theconnection pad 21 surrounds and is electrically connected to theconductor 111.

In this embodiment, a metallization layer 22 is provided on the surfaceof the circuit layer 20. The metallization layer 22 is a metal such astin or silver.

FIG. 13 is a fourth embodiment of the circuit board 300 of the presentdisclosure. The circuit board 300 includes a substrate 10 and twocircuit layers 20 disposed on both sides of the substrate 10.

The substrate 10 has a conductive hole 12 penetrating therethrough. Aconductor 111 is provided in the conductive hole 12.

The substrate 10 is provided with a groove 15 on both sides. The groove15 includes a concave portion 151. The concave portion 151 is located atthe conductive hole 12, and the diameter of the concave portion 151 islarger than the diameter of the conductive hole 12.

Each of the two circuit layers 20 is disposed in a corresponding one ofthe grooves 15. Each of the two circuit layers 20 includes a connectionpad 21 located in the concave portion 151. The two circuit layers 20 areelectrically connected through the conductor 111.

The manufacturing method of the circuit board of the present disclosureis relatively simple and the manufacturing cost is low. The circuit ofthe manufactured circuit board 200/300 is formed in the groove 15, andthe groove 15 is formed by laser ablation, therefore, the line thicknessof the circuit layer 20 is stable and the precision is higher. Theconnection pad 21 of the circuit board 200/300 of the present disclosureis a conductive protrusion to improve the conductive yield.

In addition, those skilled in the art can also make other changes withinthe spirit of the present disclosure. Of course, these changes made inaccordance with the spirit of the present disclosure should be includedin the scope claimed by the present disclosure.

What is claimed is:
 1. A circuit board manufacturing method comprising:providing (1) providing a substrate, and making a hole in the substrateto form a through hole; (2) filling the through hole with a conductor toform a conductive hole; (3) providing a peelable film to cover one sideof the substrate; (4) forming a groove in the peelable film and thesubstrate by laser ablation, the groove comprising a concave portion,the concave portion located at the conductive hole, and a diameter ofthe concave portion being larger than a diameter of the conductive holeto expose a portion of the conductor; (5) performing a surface treatmenton a side wall and a bottom wall of the groove to improve roughness; (6)removing the peelable film; (7) forming a seed layer on the side walland the bottom wall of the groove; (8) making a circuit layer in thegroove to obtain a circuit board unit, the circuit layer comprising aconnection pad located in the concave portion, the connection pad shapedas a conductive protrusion which surrounds and is electrically connectedto the conductor; (9) repeating step (1) to step (8) at least once; and(10) laminating at least two of the circuit board units.
 2. The circuitboard manufacturing method according to claim 1, wherein: in step (5),the side wall and the bottom wall of the groove are processed by aplasma surface treatment machine.
 3. The circuit board manufacturingmethod according to claim 1, wherein: in step (7), the seed layer isformed by chemical vapor deposition or physical vapor deposition.
 4. Thecircuit board manufacturing method according to claim 1, wherein: afterstep (8) and before step (9), the method further comprises a step offorming a metallization layer on a surface of the circuit layer.
 5. Thecircuit board manufacturing method according to claim 1, wherein: instep (1), one side of the substrate is connected to a carrier boardthrough a separable film.
 6. A circuit board comprising at least twostacked circuit board units, each of the circuit board units comprisinga substrate and a circuit layer, the substrate provided with aconductive hole penetrating therethrough, the conductive hole providedwith a conductor therein, one side of the substrate provided with agroove, the groove comprising a concave portion, the concave portionlocated at the conductive hole, a diameter of the concave portiongreater than a diameter of the conductive hole to expose a portion ofthe conductor, the circuit layer comprising a connection pad located inthe concave portion, the connection pad shaped as a conductiveprotrusion which surrounds and is electrically connected to theconductor, the circuit layer located in the groove, and the conductivehole electrically connecting the circuit layers of the at least twostacked circuit board units.
 7. The circuit board according to claim 6,wherein: a metallization layer is provided on a surface of the circuitlayer.
 8. A circuit board manufacturing method, comprising: providing asubstrate, and opening a hole in the substrate to form a through hole;filling the through hole with a conductor to form a conductive hole;providing two peelable films covering opposite sides of the substraterespectively; forming grooves in the two peelable films and both sidesof the substrate by laser ablation, each groove comprising a concaveportion, the concave portion located at the conductive hole, and adiameter of the concave portion being larger than a diameter of theconductive hole to expose a portion of the conductor; performing asurface treatment on a side wall and a bottom wall of the grooves toimprove roughness; removing the two peelable films; forming a seed layeron the side wall and the bottom wall of each of the two grooves; forminga circuit layer in each of the two grooves to obtain a circuit board,the circuit layer comprising a connection pad in the concave portion,the connection pad shaped as a conductive protrusion which surrounds andis electrically connected to the conductor.
 9. A circuit boardcomprising a substrate and two circuit layers, wherein: the substrate isprovided with a conductive hole, the conductive hole is provided with aconductor, two sides of the substrate are provided with a groove, eachof the two circuit layers is respectively provided in a correspondingone of the grooves, each of the grooves comprises a concave portion, theconcave portion is located at the conductive hole, a diameter of theconcave portion is larger than a diameter of the conductive hole toexpose a portion of the conductor, the circuit layer comprise aconnection pad located in the concave portion, the connection pad isshaped as a conductive protrusion, and the conductive hole electricallyconnects the two circuit layers.